1. Field of the Invention
The present invention relates to fuel injectors, and more particularly, to fuel passages within a feed arm for a multiple circuit fuel injector of a gas turbine engine.
2. Description of Related Art
Typical fuel injectors include multiple fuel flow passages, allowing for the power output of the gas turbine engine to be more easily adjusted. For example, a fuel injector may have a primary fuel flow passage and a secondary fuel flow passage, with both passages being used during higher power operation and only the primary fuel flow passage being used during lower power operation.
Fuel injectors also typically include heat shields surrounding the tubular fuel passages to protect the fuel flowing through the passages from the heat generated in the combustion chamber as well as the heat of compressor discharge air. These heat shields help to prevent coking, the breaking down of the liquid fuel into solid deposits. Coking is likely to occur when the temperature of the wetted walls in a fuel passage exceeds a maximum value. When coking occurs, solid deposits can form within the fuel flow passage, which restricts the flow of fuel through the passage and can render the fuel injector ineffective or unusable. Fuel coking within the nozzle can cause reductions in fuel flow. This can lead to undesirable thermal gradients within the combustion system causing hardware distress and ultimately failure.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved thermal management for fuel injectors. The present disclosure provides a solution for this need.